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Tutorial: generic implementation
Hands-on tutorial for generic implementation – one abstract BO and one rule for many concrete BOs (number ranges, sum calculation).
TUTORIAL APPLICATION DEVELOPER UPDATED: JUL 2026 APPLIES TO NUCLOS 4.2026.X
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Overview
Goal: create a generic business object and implement a generic rule.
Prerequisite: at least two business objects with similar fields (e.g. a running number).
The generic implementation replaces repeated rule code branched by instanceof with one abstract BO serving several concrete BOs.
Example 1: number ranges
Several BOs (quote, order, delivery note, purchase order) receive an automatic number on creation. Previously solved via instanceof:
public void insert(InsertContext context) throws BusinessException {
final Modifiable<?> businessObject = context.getBusinessObject(Modifiable.class);
if (businessObject instanceof Angebot) {
((Angebot) businessObject).setAngebotsnr(NummernkreiseLogik.getNextValue(Angebot.class));
} else if (businessObject instanceof Auftrag) {
((Auftrag) businessObject).setAuftragsnr(NummernkreiseLogik.getNextValue(Auftrag.class));
} else if (businessObject instanceof Lieferschein) {
((Lieferschein) businessObject).setLieferscheinnr(NummernkreiseLogik.getNextValue(Lieferschein.class));
} else if (businessObject instanceof Bestellung) {
((Bestellung) businessObject).setBestellnr(NummernkreiseLogik.getNextValue(Bestellung.class));
}
}
1. Create the generic BO
Create a new generic BO Nummerierbar in the business object wizard with exactly one attribute Nummer (no layout/permissions) and assign it to a nuclet.
Data type
The data type of the generic attribute must match that of the fields in the implementing BOs.
2. Configure the mapping
For each implementing BO create a record with the attribute mapping (e.g. Nummer → order number). Nuclos generates the class Nummerierbar.java with generic getters/setters:
import org.nuclos.businessentity.*;
import org.nuclos.api.businessobject.Dependent;
import org.nuclos.api.businessobject.Flag;
import org.nuclos.api.UID;
import org.nuclos.api.businessobject.GenericBusinessObject;
import java.util.List;
import java.util.ArrayList;
import java.util.HashSet;
/**
* BusinessObject: Nummerierbar
*<br>
*<br>Nuclet: org.nuclet.tulteclico
*<br>DB-Name: [generic]
*<br>Editable: true
*<br>Localized: false
*<br>Statemodel: false
**/
public class Nummerierbar implements GenericBusinessObject<Long> {
private org.nuclos.api.businessobject.BusinessObject<Long> businessObject;
public Nummerierbar(org.nuclet.tulteclico.Lieferschein businessObject) {
this.businessObject = businessObject;
}
public Nummerierbar(org.nuclet.tulteclico.Bestellung businessObject) {
this.businessObject = businessObject;
}
public Nummerierbar(org.nuclet.tulteclico.Auftrag businessObject) {
this.businessObject = businessObject;
}
public Nummerierbar(org.nuclet.tulteclico.Angebot businessObject) {
this.businessObject = businessObject;
}
public org.nuclos.api.UID getEntityUid() {
return businessObject.getEntityUid();
}
public org.nuclos.api.businessobject.BusinessObject<Long> getBusinessObject() {
return businessObject;
}
public java.lang.String getEntity() {
return businessObject.getEntity();
}
public java.lang.Long getId() {
return businessObject.getId();
}
public java.lang.Integer getVersion() {
return businessObject.getVersion();
}
public boolean isInsert() {
return businessObject.isInsert();
}
public boolean isUpdate() {
return businessObject.isUpdate();
}
public boolean isDelete() {
return businessObject.isDelete();
}
/**
* Getter-Method for attribute: changedAt
*<br>
*<br>Entity: Nummerierbar
*<br>DB-Name: DATCHANGED
*<br>Data type: org.nuclos.common2.InternalTimestamp
*<br>Localized: false
*<br>Output format: null
*<br>Scale: null
*<br>Precision: null
**/
public java.util.Date getChangedAt() {
// all implemented BOs:
if (this.businessObject instanceof org.nuclet.tulteclico.Lieferschein) {
return ((org.nuclet.tulteclico.Lieferschein) this.businessObject).getChangedAt();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Bestellung) {
return ((org.nuclet.tulteclico.Bestellung) this.businessObject).getChangedAt();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Auftrag) {
return ((org.nuclet.tulteclico.Auftrag) this.businessObject).getChangedAt();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Angebot) {
return ((org.nuclet.tulteclico.Angebot) this.businessObject).getChangedAt();
}
// not implemented attribute:
return null;
}
/**
* Getter-Method for attribute: changedBy
*<br>
*<br>Entity: Nummerierbar
*<br>DB-Name: STRCHANGED
*<br>Data type: java.lang.String
*<br>Localized: false
*<br>Output format: null
*<br>Scale: 255
*<br>Precision: null
**/
public java.lang.String getChangedBy() {
// all implemented BOs:
if (this.businessObject instanceof org.nuclet.tulteclico.Lieferschein) {
return ((org.nuclet.tulteclico.Lieferschein) this.businessObject).getChangedBy();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Bestellung) {
return ((org.nuclet.tulteclico.Bestellung) this.businessObject).getChangedBy();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Auftrag) {
return ((org.nuclet.tulteclico.Auftrag) this.businessObject).getChangedBy();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Angebot) {
return ((org.nuclet.tulteclico.Angebot) this.businessObject).getChangedBy();
}
// not implemented attribute:
return null;
}
/**
* Getter-Method for attribute: createdAt
*<br>
*<br>Entity: Nummerierbar
*<br>DB-Name: DATCREATED
*<br>Data type: org.nuclos.common2.InternalTimestamp
*<br>Localized: false
*<br>Output format: null
*<br>Scale: null
*<br>Precision: null
**/
public java.util.Date getCreatedAt() {
// all implemented BOs:
if (this.businessObject instanceof org.nuclet.tulteclico.Lieferschein) {
return ((org.nuclet.tulteclico.Lieferschein) this.businessObject).getCreatedAt();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Bestellung) {
return ((org.nuclet.tulteclico.Bestellung) this.businessObject).getCreatedAt();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Auftrag) {
return ((org.nuclet.tulteclico.Auftrag) this.businessObject).getCreatedAt();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Angebot) {
return ((org.nuclet.tulteclico.Angebot) this.businessObject).getCreatedAt();
}
// not implemented attribute:
return null;
}
/**
* Getter-Method for attribute: createdBy
*<br>
*<br>Entity: Nummerierbar
*<br>DB-Name: STRCREATED
*<br>Data type: java.lang.String
*<br>Localized: false
*<br>Output format: null
*<br>Scale: 255
*<br>Precision: null
**/
public java.lang.String getCreatedBy() {
// all implemented BOs:
if (this.businessObject instanceof org.nuclet.tulteclico.Lieferschein) {
return ((org.nuclet.tulteclico.Lieferschein) this.businessObject).getCreatedBy();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Bestellung) {
return ((org.nuclet.tulteclico.Bestellung) this.businessObject).getCreatedBy();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Auftrag) {
return ((org.nuclet.tulteclico.Auftrag) this.businessObject).getCreatedBy();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Angebot) {
return ((org.nuclet.tulteclico.Angebot) this.businessObject).getCreatedBy();
}
// not implemented attribute:
return null;
}
/**
* Getter-Method for attribute: nummer
*<br>
*<br>Attribute Information:<br>
*<br>
*<br>Entity: Nummerierbar
*<br>DB-Name: [generic]
*<br>Data type: java.lang.String
*<br>Localized: false
*<br>Output format: null
*<br>Scale: 255
*<br>Precision: null
**/
public java.lang.String getNummer() {
// all implemented BOs:
if (this.businessObject instanceof org.nuclet.tulteclico.Lieferschein) {
return ((org.nuclet.tulteclico.Lieferschein) this.businessObject).getLieferscheinnr();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Bestellung) {
return ((org.nuclet.tulteclico.Bestellung) this.businessObject).getBestellnr();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Auftrag) {
return ((org.nuclet.tulteclico.Auftrag) this.businessObject).getAuftragsnr();
}
if (this.businessObject instanceof org.nuclet.tulteclico.Angebot) {
return ((org.nuclet.tulteclico.Angebot) this.businessObject).getAngebotsnr();
}
// not implemented attribute:
return null;
}
/**
* Setter-Method for attribute: nummer
*<br>
*<br>Attribute Information:<br>
*<br>
*<br>Entity: Nummerierbar
*<br>DB-Name: [generic]
*<br>Data type: java.lang.String
*<br>Localized: false
*<br>Output format: null
*<br>Scale: 255
*<br>Precision: null
**/
public void setNummer(java.lang.String pNummer) {
// all implemented BOs:
if (this.businessObject instanceof org.nuclet.tulteclico.Lieferschein) {
((org.nuclet.tulteclico.Lieferschein) this.businessObject).setLieferscheinnr(pNummer);
}
if (this.businessObject instanceof org.nuclet.tulteclico.Bestellung) {
((org.nuclet.tulteclico.Bestellung) this.businessObject).setBestellnr(pNummer);
}
if (this.businessObject instanceof org.nuclet.tulteclico.Auftrag) {
((org.nuclet.tulteclico.Auftrag) this.businessObject).setAuftragsnr(pNummer);
}
if (this.businessObject instanceof org.nuclet.tulteclico.Angebot) {
((org.nuclet.tulteclico.Angebot) this.businessObject).setAngebotsnr(pNummer);
}
}
}
3. Generic rule
In the server rule manager create a rule on creation, assign it to all implementing BOs (order/conditions as usual) and, instead of instanceof, fetch the generic BO from the context:
public void insert(InsertContext context) throws BusinessException {
Nummerierbar n = context.getBusinessObject(Nummerierbar.class);
n.setNummer(NummernkreiseLogik.getNextValue(n.getEntityUid()));
}
Example 2: sum calculation in document positions
Quote, order and invoice each have a subform with positions and the rule total = unit price × quantity. Instead of doing this per BO, it is solved generically.
Two generic BOs
- Beleg (document, totals),
- Belegposition (unit price, quantity, total + reference to the document).
After mapping, Nuclos generates Beleg.java and Belegposition.java. The latter maps e.g. getMenge() to getPos() of the respective concrete BO and provides getBelegposition() as a list.
Generic rule
public void save(SaveContext context) throws BusinessException {
Belegposition pos = context.getBusinessObject(Belegposition.class);
BigDecimal einzel = pos.getEinzelpreis();
Integer menge = pos.getMenge();
if (einzel != null && menge != null) {
pos.setGesamtpreis(einzel.multiply(new BigDecimal(menge)));
}
}
One code for all
The rule is assigned to all relevant position BOs – one implementation covers all document types.
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